# $radiansToDegrees (aggregation)¶

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## Definition¶

`$radiansToDegrees`

¶*New in version 4.2*.Converts an input value measured in radians to degrees.

`$radiansToDegrees`

has the following syntax:{ $radiansToDegrees: <expression> } `$radiansToDegrees`

takes any valid expression that resolves to a number.By default

`$radiansToDegrees`

returns values as a`double`

.`$radiansToDegrees`

can also return values as a 128-bit decimal as long as the`<expression>`

resolves to a 128-bit decimal value.For more information on expressions, see Expressions.

## Behavior¶

`null`

, `NaN`

, and `+/- Infinity`

¶

If the argument resolves to a value of `null`

or refers to a field
that is missing, `$radiansToDegrees`

returns `null`

. If
the argument resolves to `NaN`

, `$radiansToDegrees`

returns `NaN`

. If the argument resolves to negative or positive
infinity, `$radiansToDegrees`

negative or positive infinity
respectively.

Example | Results |
---|---|

`{ $radiansToDegrees: NaN }` | `NaN` |

`{ $radiansToDegrees: null }` | `null` |

`{ $radiansToDegrees : Infinity}` | `Infinity` |

`{ $radiansToDegrees : -Infinity }` | `-Infinity` |

## Example¶

The `trigonometry`

collection contains a document that contains
three angles measured in radians:

{ "angle_a" : NumberDecimal("0.9272952180016122324285124629224290"), "angle_b" : NumberDecimal("0.6435011087932843868028092287173227"), "angle_c" : NumberDecimal("1.570796326794896619231321691639752") }

The following aggregation operation uses the
`$radiansToDegrees`

expression to convert each value to
its degree equivalent and add them to the input document using the
`$addFields`

pipeline stage.

db.trigangles.aggregate([ { $addFields: { "angle_a_deg" : { $radiansToDegrees : "$angle_a"}, "angle_b_deg" : { $radiansToDegrees : "$angle_b"}, "angle_c_deg" : { $radiansToDegrees : "$angle_c"} } } ])

The operation returns the following document:

{ "_id" : ObjectId("5c50aec71c75c59232b3ede4"), "angle_a" : NumberDecimal("0.9272952180016122324285124629224290"), "angle_b" : NumberDecimal("0.6435011087932843868028092287173227"), "angle_c" : NumberDecimal("1.570796326794896619231321691639752"), "angle_a_deg" : NumberDecimal("53.13010235415597870314438744090659"), "angle_b_deg" : NumberDecimal("36.86989764584402129685561255909341"), "angle_c_deg" : NumberDecimal("90.00000000000000000000000000000000") }

Since `angle_a`

, `angle_b`

, and `angle_c`

are stored as
128-bit decimals, the output of
`$radiansToDegrees`

is a 128-bit decimal.